1. Field of the Invention
The present invention generally relates to an electrophotographic image processing machine such as, for example, an electrophotographic color copying machine, and more particularly to the electrophotographic image processing machine equipped with means for avoiding forgery of valuable papers such as monetary papers and securities.
2. Description of the Prior Art
The Japanese Laid-open Patent Publication No. 2-210591 discloses an image processing machine having a capability of avoiding forgery of monetary papers. According to this prior art image processing machine, detection is made of an image pattern by detecting the position of the original, followed by comparison of the detected image patter with a standard pattern stored in the system to determine the similarity. This prior art image processing machine determines the nature of the original, i.e., whether or not the original is a monetary paper, according to the degree of similarity. Specifically, In this prior art image processing machine, a pattern matching technique is employed to compare the seal (the Seal of the Governor of the Bank of Japan) imprinted on the monetary paper with that stored in a memory.
The Japanese Laid-open Patent Publication 64-61777 discloses a copying machine having a capability of disabling a copying function that works out when one attempts to make a copy of the monetary paper. This publication describes that, when an image date read out matches with a predetermined density or pattern, the copying function is disabled, but has failed to disclose a specific verification method.
The image processing machine disclosed in the first mentioned publication is satisfactory in that, when the valuable paper such as, for example, the monetary paper is placed on a document support of the machine, the presence of the valuable paper can be recognized to avoid forgery. However, in the event that the monetary paper is placed on the document support with a portion thereof concealed or separated pieces of the monetary paper are placed on the document support, there is no way to avoid forgery.
On the other hand, the second mentioned publication disclose no specific verification method as mentioned above. In other word, no disclosure is made in this second mentioned publication as to how verification can be correctly and with no error made from a portion of the original, and therefore, it appears difficult to accurately determine the nature of the original placed on the document support, that is, whether or not it is a monetary paper.